camarols1

iTrader: (17)

That makes sense Stevieturbo.
Basically run the "piggyback ecu" in open loop so it just adds additional fuel
when required.
I may try this idea for an additional 4 injectors to be controlled by an aftermarket
piggyback unit that someone gave me to try out.

stevieturbo

With only 4 injectors....make sure they are positioned such that fuel distribution will be even.

8 would naturally be better.

kbracing96

iTrader: (25)

You could do something like this..



They are planing on putting this on a twin turbo stock 6l, non intercooled, running strait meth thought the 8 injectors in the vic jr. when in boost and on gas though the 4 injectors in the tb adapter when not in boost. There going to use megasquirt to control it all since it has 2 VE table that will control different sets of injectors at the same time. Preety cool

http://www.performancetrucks.net/for...d.php?t=413016

http

Vents

iTrader: (9)

thats pretty wicked cool.

I think that mega squirt would be the most viable option for dual and or staged injection on the cheap. Great ideas in here.

camarols1

iTrader: (17)

That elbow is what I was thinking of using, but with one air inlet.
I would like to be able to push e85 to 1,000RWP running (8) 96lb injectors
full time via the stock pcm, then add the additional (4) under boost only via a piggyback pcm.
I am resisting the jump to using 160# injectors because I want to be able to drive the car on gasoline when needed. E85 is not at every corner station.
Also, at only 6.0 litres, I don't think the 160# units will be as nice to drive on the street.

cast iron

To expand on this, you could even take it as far as running HPT 2 bar/3 bar or EFI Live COS5 or what have you on the additional ECU, and trigger fueling off of MAP input..

stevieturbo

Using a 2nd factory ecu, would be way over complicated.

The point was to keep it simple.

Doubledip

Yes thanks Steve ... as i said you can never say never but would be a pain with 2 factory ecu's as mentioned before.

the whole idea from the original post was can you run 2 hi impedance injectors from each injector driver on a stock ECU.

if you were to go down the 2 ecu path might as well go low impedance injectors and driver box or after market computer all together....

anyway thanks for eveyones input as they have all been great... at least if i need more answers for further questions in the future i know where to come

Frank02L

iTrader: (1)

Why not put a low impedence injector driver on it and put the right size injectors in it and be done.

My Ford ECU is running 160#s and we've set two GM ECUs up with 96# and a driver. If we step up the motor and bigger turbo then we're going to put 160s in one of the GM ECUs as well.

Not to mention that by the time you buy 16 60# injectors you can buy 8 160s and the full plug and play injector driver setup from Racetronix.

Doubledip

with yours do you run EGT's on each cylinder? would be interesting to know the differences you get with each cylinder.

Frank02L

iTrader: (1)

No, I dont worry with the EGTs.

Doubledip

ok no worries just with the driver boxes when running lo impedance injectors we have seen masssive differences between cylinders of upto 200 degrees. but with out them only round 20 degrees which is liveable

Beaflag VonRathburg

iTrader: (176)

I see what you are saying about one PCM changing the things the other does. The second one would strictly be used for fueling it's own injectors though like many people talked about with the piggy back setup. I was thinking about doing this because it's really cheap. You can get a PCM for about $75. You'd just need extra wiring and bam you're setup. The tuning issue would be a major pain in the ***, but if you have lots of free time like I do it would be worth it.

I don't know a lot about tuning, but would there be ways to cut out certain readings from 1 PCM and only have them going to the other? Like both wouldn't need knock sensors.

cast iron

Don't connect and delete the code?

For fuel you'd need your basics: MAF, Crank, Cam, MAP, IAT, ECT, possibly O2 sensors if you wanted to run closed loop

Using a factory PCM you are KEEPING sequential injection. It's always better to inject near a closed intake valve. Less fuel puddling to parts of the intake track, and better atomization = higher efficiency = more power.

If you need a large amount of fuel, you need a large injector. For a pure race car this isn't a problem as you can let it idle rich, raise the idle, etc. For a street car this becomes a huge problem. By using dual PCM's you maintain efficient fuel delivery, and the ability to keep factory sized injectors to maintain spray pattern, well wetting characteristics, etc while being able to use your second "stage" for when its needed, ala boost.

Tuning will be interesting, along with the wiring and the affects of splicing into the vitals, but should be doable.

I'm really interested in the project, let me know if I can help.

stevieturbo

So with the factory ecu, can, and have any of you optimised your injection timing on the dyno ?

All a second ecu would need, in its most basic form, is crank and a load parameter. The map doesnt need to be anything fancy at all. It just needs to dump fuel in progressively.

You can do all fine tuning with the original ecu, and use the secondary for coarse tuning if you will.

I dont, and never have used sequential injection on my car. Aside from low rpm operation, and perhaps some emissions, I dont believe it will make one bit of difference to how it performs.

And running a piggyback, just firing injectors in batch....will still allow you to retain sequential under light load, low rpm anyway.

Injecting against a closed valve, or open valve....thats another debate entirely.


But as others have suggested. Given the physical difficulties of fitting multiple injectors....low impedance and driver box would be a sensible option.

Doubledip

yes i know the easy option is big lo impedance injectors with a driver box but we have tried that and have see huge differences in the EGT's of the cylinders like 200 degrees... this is not good when trying to get everything out of a drag car down the 1/4....

with the ls1 pcm and no driver box and hi impedance injectors it was only varying 20 degrees which is fine... does anyone else here run EGT's .. i am surprised if no one else does on the race cars .. maybe if you did some of you would be scared at the numbers they are showing

10sec_rx7

as doubleip has said we tryed the driver box and was actually scared at the numbers the data logger was showing, i ripped the driver box off and put the 60's back in and the numbers were all with in 20deg,

i have made the patch harness to test the double injectors per bank which i will try this afternoon on my road car.

ill let you all know

Doubledip

been speaking to 10sec_rx7 and after trying the 16 injectors on 1 LS1 PCM if if doesnt work we will go this way of 2 x LS1 PCM's one controlling the whole lot and the other controlling just fuel.

and thanks everyone for all you suggestions and comments.. as 10sec_rx7 said will keep you posted on which ever way we go..

Beaflag VonRathburg

iTrader: (176)

^ Sounds interesting. I'll be watching.

10sec_rx7

i know the 2 pcms will work no problems at all, very simple to setup and use,
one will be running a set of the 79lb racetronix injectors and the other a set of stock LS6injectors, this will give us another 400hp worth of injectors with out spending a cent on new ones,

this will give us scope for upto around 1700hp and gets rid of all the head ***** of running a after market ecu, both PCM's will run the HP tuners 3 bar OS with real time tuning which we have been running on the single PCM since we put the car together

doubelip will sort us out with a custom loom to join together what we need to and have a seperate water and air temp sensor for each PCM, ill just mount the 2 PCM's back to back and have 2 obd ports

we have a totally seperate data logging system so logging is not a problem with the 2 PCM's